Ceramic honeycomb structures are widely used as anti-pollutant devices in exhaust systems of automotive vehicles, both as catalytic converter substrates in automobiles and diesel particulate filters in diesel-powered vehicles. After being extruded and fired, the finished ceramic structures may be subjected to a coating process that coats the gas contacting surfaces with a washcoat, possibly containing catalytic metals.
Before entering the wash coat process, one may create a mark onto the ceramic honeycomb for identification and to ensure traceability of the article all along the process flow. This mark may be printed in the form of a bar code, such as a two-dimensional data matrix barcode that includes manufacturing information relating to the process steps seen by the honeycomb.
Exemplary marking methods include laser marking and inkjet printing using a heat resistant ink or coating. To the extent a printed mark is created on the honeycomb, the honeycomb thereafter undergoes catalyst coating and heat treatment. Generally, the honeycomb bodies may be subjected to additional heating steps in which the honeycombs are fired again to a lower temperature, e.g., at 300° C. to 700° C. Accordingly, it is desired to develop a coating for marking which is not deteriorated by chemical and/or heat treatment.